1. Field of the Invention
This invention relates to an ink jet recording head for use in a recording apparatus that performs a recording operation by discharging recording liquid such as ink from a discharge port to form liquid droplets. More particularly, this invention relates to a recording element substrate for use in the ink jet recording head, a wiring substrate that connects the recording device substrate with a power source, and so forth. It should be noted that the ink jet recording head according to the present invention may be applied to an ordinary printing apparatus and other apparatuses such as a copying machine, a facsimile with a communication system, and a word processor having a printing section, and may also be applied to an industrial recording apparatus that is compositely combined with various processing units.
2. Related Background Art
Conventionally, an ink jet recording head is comprised of pads that receive driving pulses for driving liquid discharge elements (e.g. piezoelectric elements and bubble generating electrothermal converting elements) provided in the head. Terminals provided at a head mounting position of a printer are brought into contact with the pads when the ink jet recording head is detachably mounted on the printer. The pads of the ink jet recording head will be increased reasonably according to the increase in the number of liquid discharge elements.
For example, an ink jet recording head disclosed in U.S. Pat. No. 5,610,635 has a memory element and a pad portion disposed in a flexible cable that is directly connected with the head.
The number of discharge elements in an ink jet recording head has increased from 64 for monochromatic recording to 128 or more. In the case of a recording head capable of multicolor recording, the number of discharge elements have been increased. Accordingly, the number of pads required for the recording head has been increased.
On the other hand, an ink jet recording head is usually provided with a holder that is detachably mounted on the head in order to receive discharge ink from a tube or a tank. Among various kinds of ink jet recording heads, a head chip utilizing thermal energy has the advantage of being small in size. The use of such a head chip reduces the size of a plurality of recording heads even if the number of pads is increased.
If forty pads are arranged in the flexible cable of the recording head disclosed in the U.S. Pat. No. 5,610,635 in the case where the number of pads in the ink jet recording head is increased as stated above, the pads must be arranged along the length of the flexible cable since the width of the flexible cable is fixed due to the limitation on the width of the recording head itself. In this case, eight rows of five pads arranged along the width direction of the flexible cable must be arranged along the length direction of the flexible cable. As a result, if the ink jet recording head is electrically connected with a printer body, contact pressure is varied according to the positions of the pads and terminals when a plurality of pads is brought into contact with a plurality of terminals. This increases the poor contact between the pads and the terminals.
Moreover, if the recording head is constructed as disclosed in the specification of the above patent, a memory element or the like provided in the flexible cable may become one of factors that badly affect the contact between the pads of the recording head and the terminals of the carriage.
Further, there is no prior art that enables the proper arrangement of pads according to different structures of heads, and it is therefore necessary to develop the technique for arranging pads reasonably and properly.
It is therefore an object of the present invention to provide an ink jet recording head, which is detachably mounted in a recording head and has a plurality of input terminals for receiving electric signals from a recording apparatus body, the ink jet recording apparatus being capable of preventing the poor contact between the input terminals of the recording head and the terminals of the recording apparatus body in electric connection thereof even if the number of the input terminals is increased.
In order to attain the above object, there is provided an ink jet recording head, comprising: a plurality of recording element substrates having a plurality of recording elements for discharging a recording liquid, and a supply port for supplying the recording liquid to the recording elements; a supporting member for supporting the plurality of recording element substrates; an electric contact substrate having a plurality of input terminals electrically connected to terminals of a recording apparatus body, and being fixed to the supporting member; an electric wiring tape connected to the plurality of the recording element substrates and the electric contact substrate such that the input terminals of the electric contact substrate are electrically connected to the recording elements of the recording element substrates; and in which the width of the electric contact substrate is wider than that of the electric wiring tape in a lateral direction perpendicular to a longitudinal direction in which the electric contact substrate and the electric wiring tape are arranged, and the input terminals are arranged in the lateral direction and the longitudinal direction on one surface of the electric contact substrate, and a relationship of m greater than n is satisfied if the maximum number of the input terminals in the lateral direction is assumed to be m and the maximum number of input terminals in the longitudinal direction is assumed to be n. Preferably, n is equal or less than 5.
It is preferred that the maximum number m of the input terminals are arranged in the lateral direction on one surface of the electric contact substrate, and rows of the m input terminals arranged in the lateral direction and extending in the lateral direction are arranged in the longitudinal direction in the same number as the maximum number n in the longitudinal direction.
According to the invention described above, in the ink jet recording head in which the respective recording element substrates are electrically connected to the electric contact substrate fixed on the supporting member supporting the recording element substrates through the electric wiring tape, the width of the electric contact substrate is wider than that of the electric wiring tape in the lateral direction perpendicular to the direction in which the electric contact substrate and the electric wiring tape are arranged. This reduces the number of input terminals on the electric contact substrate, and arranges a plurality of input terminals on the electric contact substrate while preventing them from being arranged in the form of an oblong. More specifically, the input terminals are arranged in the lateral and longitudinal directions on one surface of the electric contact substrate, and the relationship of m greater than n is satisfied if the maximum number of the input terminals in the lateral direction is assumed to be m and the maximum number of input terminals in the longitudinal direction is assumed to be n. Therefore, the input terminals are arranged in the form of a rectangle on the electric contact substrate. In the case where the input terminals are arranged in the form of a rectangle, the farthest input terminals from the recording element substrates among the input terminals on the electric contact substrate can be closer to the recording element substrates than in the case where the input terminals are arranged in the form of an oblong. If the ink jet recording head is mounted on the carriage of the recording apparatus body or the like, a portion of the ink jet recording head by the side of the recording element substrates is positioned and fixed. Thus, if the input terminals are arranged in the form of a rectangle on the electric contact substrate so that the farthest input terminals from the recording element substrates among the input terminals on the electric contact substrate can be close to the recording element substrates, the contact pressure can be prevented from varying according to the positions of the terminals when the input terminals and the terminals of the carriage are brought into contact with one another in electric connection thereof. This significantly reduces the poor contact between the input terminals on the electric contact substrate of the ink jet recording head and the terminals of the recording apparatus body in the electric connection thereof, and reduces the size and cost of the ink jet recording head.
It is preferred that one of the recording element substrates is a black recording element substrate for use in discharging a black recording liquid, and among the input terminals on the electric contact substrate, only the input terminals electrically connected to the black recording element substrate are arranged in an outermost row at an opposite side of the electric wiring tape.
If only the input terminals electrically connected to the black recording element substrate for use in discharging a black recording liquid among the input terminals on the electric contact substrate are arranged in the outermost row at the opposite side of the electric wiring tape as stated above, only erasing the outermost row at the opposite side of the electric wiring tape among the input terminals on the electric contact substrate enables the manufacture of an ink jet recording head having no black recording element substrate without the need for redesigning the electric contact substrate.
It is also preferred that the plurality of the input terminals are arranged such that head driving voltage input terminals, logic system voltage input terminals, and ground terminals are not arranged adjacently to one another.
If the plurality of the input terminals on the electric contact substrate is arranged such that head driving voltage input terminals, logic system voltage input terminals, and ground terminals are not arranged adjacently to one another as stated above, the smoking can be prevented when the contact portion of the input terminal is short-circuited when ink is adhered to the surface of the electric contact substrate where the input terminals are formed.
In order to attain the above object, there is provided an ink jet recording apparatus comprising: a carriage having a plurality of terminals coming into contact with the input terminals of the ink jet recording head to be electrically connected to the input terminals in a state where the above-mentioned ink jet recording head is detachably mounted on the ink jet recording apparatus; and in which each of the recording element substrates of the ink jet recording head discharges a recording liquid in connection with scanning of the carriage to thereby make a record on a medium to be recorded.